Assessment of Cryptococcus albidus for biopulping of eucalyptus.

Cryptococcus albidus shows delignification activity in nature. It was used for the biopulping of eucalyptus wood (Eucalyptus grandis) to access its potential for industrial application in the pulp and paper industry. Enzyme analysis on days 15, 30, and 60 showed the presence of laccase and xylanase as key enzymes. The production of endo-glucanase (CMCase) and exo-glucanase (FPase) was very low. Scanning electron microscopy (SEM) showed the surface colonization of wood and loosening of wood fibers in C. albidus-treated samples. Fourier-transformation infrared spectroscopy (FT-IR) indicated the chemical modification of eucalyptus wood. Denaturing gradient gel electrophoresis (DGGE) analysis on days 15, 30, and 60 confirmed the presence of C. albidus throughout the experiments. Cryptococcu albidus was able to suppress the growth of a native population. Further, after 60 days both the control and treated eucalyptus wood chips were given kraft pulping treatment. The kappa number of pulp of control wood was 21 and for treated wood was 17. Kappa number is considered a measure of lignin content in wood; hence the treatment of eucalyptus by C. albidus (biopulping) was effective in reducing its lignin content and can be used for biopulping in the pulp and paper industry.